The sponsor of a constitutional amendment to ban same-sex marriage in Maryland undermined his cause by drafting a proposal that would also eliminate rights long afforded to gay men and lesbians, lawmakers on both sides of the debate said yesterday.

The "breathtakingly vicious scope of this amendment is such that it strips away existing protections for citizens of Maryland who happen to be gay," said Del. Luiz R.S. Simmons (D-Montgomery) as members of the House of Delegates waded into the emotional debate over same-sex marriage.

Simmons said the proposed amendment, submitted by Del. Donald H. Dwyer Jr. (R-Anne Arundel), would nullify local laws in Montgomery County and Baltimore that allow gay public employees to extend health benefits to their partners and to own property jointly. A law professor later said Dwyer's proposal was "so incoherent and sloppy" that it could inadvertently outlaw divorce.

Dwyer told the House Judiciary Committee that he had not intended to "take away any rights that are currently granted" and that he would welcome amendments to correct that.

One Republican leader said a bill with simple language would have been stronger. " 'Marriage involves one man, one woman.' That would have done it," said the lawmaker, who asked not to be named because he did not wish to publicly criticize a member of his caucus.

The questions about the proposed amendment came during the legislature's first committee hearing on the subject, which lasted seven hours and drew hundreds of spectators, more than 225 of whom sought to testify. The crowd was so boisterous at times that extra troopers from the Maryland State Police were brought in to ensure calm. Dozens waited for hours in the outdoor chill for a chance to sit in the packed hearing room.

The vast majority trekked to Annapolis to support the proposal, which, if approved by three-fifths of the lawmakers, would appear on the November ballot.

Dwyer, who has offered the measure in past years, said it took on a degree of urgency after a Baltimore Circuit Court judge ruled Jan. 20 that Maryland's 33-year-old law banning same-sex marriage is discriminatory and "cannot withstand constitutional challenge." The judge immediately stayed the decision pending an appeal.

Democratic lawmakers have said the legislature should wait until higher courts rule before putting a measure on the ballot. Gov. Robert L. Ehrlich Jr. (R) urged the legislature Monday to give the amendment "full deliberation."

As yesterday's hearing approached, a network of at least a half-dozen religious and other organizations sent out thousands of e-mails urging members to attend.

Several in the crowd held Bibles. Many wore pins advertising a marriage protection Web site.

Those who got seats in the hearing room were treated to a wide-ranging debate on judicial authority and constitutional law. They saw firsthand the tensions that surface when issues as personal as religion and sexual orientation collide with the political process.